INSKEEP: The world's largest beverage company continues to diversify. In a $2.5 billion cash deal, Coca-Cola will buy a stake in Monster, beverage maker of the popular Monster energy drink. Energy drinks are a nearly $7 billion business in the United States. Health experts have expressed concern about their high caffeine content. But energy drinks represent an area of growth in the soft drink industry, which has broadly been the target of public health campaigns. Transcript provided by NPR, Copyright NPR.